The machines of particular relevance for this invention are, for example, but without restricting the scope of the invention, those for making toilet bowls or bidets.
A prior art type of machine is described in patent EP 2 366 517 in the name of the same Applicant.
This machine comprises:                a mould made up of at least two parts designed to define, in a closed configuration, an internal cavity for casting the product;        a body for clamping and containing the mould with a tubular shape, open at the ends;        means for the relative movement between the clamping and containing body and the mould to enable a relative sliding, along a single movement axis (normally horizontal), between the clamping and containing body and the mould in a closed configuration between an operating position, where the mould and the clamping and containing body are moved away from each other, and a second operating position, where the mould and the clamping and containing body are matchingly coupled inside one another.        
In the preferred embodiment the clamping and containing body is moved towards and away from the mould.
In light of this, the tubular clamping and containing body is equipped with slides (wheels) resting on a pair of rails forming part of a supporting frame of the mould and of the clamping body.
In a solution known from patent document EP 2 366 517, the clamping and containing body is a tubular body comprising, inside it, at least one inflatable element for clamping the mould and/or containing the forces acting on the mould.
In light of this, the inflatable element (or the two or more elements, depending on the geometrical architecture of the tubular body) can be supplied with a fluid under pressure between a first non-operating, limit configuration of minimum pressure and reduced size and a second operating, limit configuration of maximum pressure and maximum size.
The frame is placed on a walkable surface and comprises:                a zone for operating and supporting the component parts of the mould and        a zone for positioning the clamping and containing body when it is moved away from the mould. The two zones are located at two different points of the frame (ends of the frame).        
In the zone for operating and supporting the mould of the frame there are service means for the cavity formed by the parts of the mould, such as means for feeding the fluid (slip) into the mould and injection of air for drainage and slip consolidation during the product casting cycle.
Also in the operating zone of the mould there are service means for a drainage system.
The drainage system is located inside porous moulds to allow the fluids that go through the inside surfaces of the mould during the casting cycle to be channelled to the outside, or to pump fluids in under pressure in the opposite direction in order to detach the moulded product from the mould walls or to recondition the mould part.
The machine components described above are positioned in a work island which comprises a servo assisted device for demoulding the product made or, alternatively, a robotized unit used for the same purpose but which can, if necessary, be designed to perform other functions for processing and finishing the moulded product.
The same robotized unit, if present, may be suitably equipped to replace parts of the mould from the operating zone of the frame.
However, the various types of machines for the production of ceramic products, including the one just described, have some drawbacks.
A first drawback is due to the impossibility of completely and effectively emptying from the cavity of the mould the excess liquids which have been left inside the cavity at the end of the casting cycle, particularly in the case of products with very complex shapes.
This problem is also caused by the fact that the mould is static and rests on a surface which is horizontal (or, at most, inclined by a few degrees relative to the walkable surface).
This feature of the machine (fixed position) results in an incomplete emptying of the excess fluids (due to gravity, slow and gradual) causing a worsening of the quality of the product or, in extreme cases, the rejection of the product.
For this reason, it is not technically possible to obtain products with complex shapes on the current machines.
Known in the prior art are some technical solutions to this problem. One of these solutions is described in document EP 0 427 184.
This document describes a pressure slip casting apparatus comprising a mould having a moulding cavity and positioned on a surface of a supporting table. The supporting table has tilting means for tilting the mould about a pivot axis by a first angle to the horizontal walkable surface. A second drawback is due to what is known as the problem of “coagulation” or “flocculation” or joint line as the level of the slip rises or “grows” inside the mould, leading to serious defects that make the quality of the end product unacceptable.
This problem arises especially in the case of liquid-cast products where there is a maximum freedom of form for the products and where, obviously, the mould may have different dimensional ratios within it and the casting cavities may be very large.
In effect, the mould cavity is not simply divided into male and female parts and, instead, the walls of the product are formed by a single surface within the mould.
The problem occurs inside the mould when the slip is fed in under pressure (usually from the bottom) and gradually “grows” inside the mould, its level rising until it completely fills the cavity.
The actual causes of the problem are still not clear although laboratory tests have indicated the following as the principal factors involved: the large volume of the mould, the relative internal air volume and the force of gravity.
Whatever the causes, the fact remains that, as the mould fills, the different substances in the slip tend to “separate out” in random fashion: that is because the slip is not a perfectly homogeneous mixture but is basically a suspension, in water, of clay and other substances with different specific weights which, as the level of the slip increases, leads to the separation between the substances of lower specific weight (tending to rise to the surface) and those of higher specific weight (tending to sink).
The separation process as the mould fills may lead to thickening or agglomeration of like substances separated from the different substances surrounding them.
The result of the agglomeration is the presence, on the surface of the rising slip, of a sort of coloured “stain” indicating the non-homogeneousness of the mixture: if this stain comes into contact with the surface of the mould, the product develops a flaw at that point.
The flaw, however, only becomes visible after the product is fired or finally glazed and appears as a clearly visible surface defect (for example in the form of a hump or recess) making it necessary to reject the product.